Geometry

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Across
  1. 5. a simple closed polygonal curve
  2. 6. a triangle having three acute angles
  3. 7. two angles that have a common side and nonoverlapping interiors
  4. 8. the union of two rays with a common endpoint
  5. 9. a convex polygon that is both equilateral and equiangular
  6. 10. an angle of measure 180 degrees
  7. 14. an angle greater than 90 degrees but less than 180 degrees
  8. 15. two angles whose sum of their measures is 180 degrees
  9. 16. a triangle having one 90 degree angle
  10. 18. an angle measuring 90 degrees
  11. 19. a rectangle with all sides of equal length
  12. 20. a curve that never touches a point more than once
Down
  1. 1. an angle greater than 180 degrees but less than 360 degrees
  2. 2. a triangle having at least two sides of the same length
  3. 3. a triangle with all sides and all angles congruent
  4. 4. two nonintersecting lines which do not belong to a common plane
  5. 11. lines intersecting at a 90 degree angle
  6. 12. two nonintersecting lines belonging to a common plane
  7. 13. a curve that ends at the same point it began
  8. 17. a quadrilateral with exactly one pair of parallel sides